I haven't been in the PWC seen very long, but I have tuned & raced a lot of cars & you don't make HP gains by changing spark plugs. As long as the plugs are in good shape, the right temp range the gap is correct, you'll never tell the difference. Some like to index their plugs, which could net a very slight increase in performance.

I haven't been in the PWC seen very long, but I have tuned & raced a lot of cars & you don't make HP gains by changing spark plugs. As long as the plugs are in good shape, the right temp range the gap is correct, you'll never tell the difference. Some like to index their plugs, which could net a very slight increase in performance.

i used to think the same thing, but people here have picked up a few RPM from indexing